阴离子交换树脂对水杨酸的吸附与解吸性能

Adsorption and Desorption Behavior of Salicylic Acid with Anion Exchange Resin

研究了717阴离子交换树脂对水中水杨酸的吸附与解吸性能,探讨了吸附的热力学和动力学特性。结果表明,树脂在pH=4~12时,吸附能力最好。等温吸附遵循Freundlich和Langmuir吸附平衡模型,为优惠吸附过程。在298~318 K条件下,水杨酸吸附量为100~120mg/g的吸附焓变为-23.4^-21.6 kJ/mol、自由能变为-7.79^-8.01 kJ/mol、吸附熵变为-52.5^-42.7 J(/K.mol)。吸附动力学符合Lagergren一级速率方程,吸附速率常数为0.039 5~0.056 1 min-1,吸附活化能为13.9 kJ/mol。颗粒内扩散是速率控制步骤之一,膜扩散也共同影响着吸附过程。树脂上吸附的水杨酸可用5%NaCl+2%NaOH溶液定量洗脱,洗脱率达99%。

Adsorption and desorption of aqueous salicylic acid solution,as well as adsorption kinetics and thermodynamics with 717 anion exchange resin were investigated.Results showed that the maximum adsorption ability of resin occurred at pH 4~12.Adsorption of salicylic acid onto resin obeyed Freundlich and Langmuir isotherm,which was a favorable adsorption.At temperature of 298~318 K and adsorption of salicylic acid of 100~120 mg/g,changes of adsorption enthalpy was measures as-23.4^-21.6 kJ/mol,free energy-7.79^-8.01 kJ/mol and entropy of adsorption-52.5^-42.7 J/（K·mol）.The adsorption kinetic data of salicylic acid onto resin fitted to Lagergren pseudo-first order rate equation,with the adsorption rate constant of 0.0395~0.056 min-1 and the adsorption activity energy of 13.9 kJ/mol.Besides the intra-particle diffusion,other process such as film diffusion also simultaneously affected the rate of adsorption.Up to 99% of salicylic acid adsorbed in the resin can be easily and quickly eluted with a 5% NaCl and 2% NaOH solution.